802.11 Wireless Local Area Network (WLAN) provides a wireless access service in a local area network (LAN). An Access point (AP), which is one of important components of WLAN, is a radio transceiver. The AP may convert data received from a wired network, such as Internet, into radio signals and transmit the radio signals, and convert received radio signals into data and forward the data to the wired network.
At present, 802.11 WLAN has been widely employed by users such as enterprises. Those users have a large amount of APs, desire reasonable security, and require high Quality of Service (Qos). Thus, effective managing measures needs employing to ensure the manageability of the network and to reduce costs of operation and management.
A conventional AP, also referred to as a Fat AP, such as an AP used widely in households nowadays, may include all of functions defined in 802.11 protocols. A Management Information Base (MIB) is a set of objects which are managed by target APs. The 802.11 protocols have established dedicated MIB standards which include not only configuration parameters of a FAT AP, e.g. parameters configured in a radio interface, such as a beacon, but also status information and status statistical information of the FAT AP, such as the number of packets transmitted to and received from a radio interface and the working status of the radio interface. In this way, a network administrator is able to configure and manage the radio interface of the FAT AP via an interface of the MIB. The following is a data structure of the MIB defined in an 802.11 protocol:
Dot11OperationEntry::=   SEQUENCE {  dot11MACAddress  MacAddress,      dot11RTSThresholdINTEGER,      dot11ShortRetryLimit INTEGER,      dot11LongRetryLimit INTEGER,      dot11FragmentationThresholdINTEGER,      dot11MaxTransmitMSDULifetime Unsigned32,      dot11MaxReceiveLifetime Unsigned32,      dot11ManufacturerID DisplayString,      dot11ProductID DisplayString }
The MacAddress denotes a Media Access Control (MAC) address of a radio interface, the RTSThreshold denotes a re-transmission time threshold of the radio interface, the ShortRetryLimit denotes a short retry limit of the radio interface, the LongRetryLimit denotes a long retry limit of the radio interface, the FragmentationThreshold denotes a fragmentation threshold of a packet transmitted via the radio interface, the MaxTransmitMSDULifetime denotes the maximum lifetime of transmitting a MAC service data unit (SDU) of the radio interface, the MaxReceiveLifetime denotes the maximum receiving lifetime of the radio interface, the ManufacturerID denotes the identifier of the manufacturer of the AP, and the ProductID denotes the product identifier of the AP. According to the MIB table, the network administrator may configure the parameters of the radio interface on the FAT AP.
It is complex to manage FAT APs, for example, a WLAN of an enterprise may include hundreds of or thousands of FAT APs and the administrator has to manage each FAT AP individually, so high costs of network operation and management may be brought out. For this reason, the Configuration and Provisioning for Wireless Access Point (CAPWAP) WorkGroup (WG) of the Internet Engineering Task Force (IETF) has proposed a concept of a Fit AP. The Fit AP mainly fulfills the real-time functions, such as packet acknowledging, Beacon message frame transmission, and cooperates with an Access Controller (AC) to implement other functions such as Fit AP management and user authentication, herein, the AC implements centralized management of APs through the CAPWAP protocol.